JPS62116247A - Method for detecting drying finish of amorphous refractory working body and drying degree measuring element for said working body - Google Patents

Abstract

PURPOSE:To make it possible to detect the drying finish point of an amorphous refractory working body, by measuring the resistance value between electrodes embedded in the amorphous refractory working body and detecting that free water in said working body is exhausted. CONSTITUTION:Each conductor of a drying degree measuring element 1 is connected to a moisture meter 12 and each thermocouple 2 is connected to a temp. recorder 13 which is, in turn, connected to a voltage recorder 14. An amorphous refractory working body is allowed to stand over a predetermined ageing period after execution and evaporates moisture generated at the time of curing. After ageing was finished, a mold frame is detached and said working body is dried under heating. By this drying under heating, free water in the working body 11 is evaporated. At this time, the output of a burner is controlled so that the working body 11 is set to temp. such that the detected saturated vapor pressure of free water does not exceed the tensile strength of the working body 11. Because of this control, the temp. information of the working body 11 is fed back to a combustion control apparatus from the thermocouple 2 and water content information is fed back to the combustion control apparatus.

Description

[Detailed Description of the Invention] [Field of Industrial Application] Currently, in steel works, monolithic refractories are used for lining blast furnace tilting troughs, tapping troughs, ladles, etc. Repairs are being carried out to replace the lining. A monolithic refractory construction body such as this lining is constructed by adding water to the mixture line, then removing the formwork and heating and drying it.

The present invention provides a method for detecting the completion of drying of a monolithic refractory construction body, which detects the end point of drying in the heating drying process of such a monolithic refractory construction body, and a method for detecting the completion of drying of a monolithic refractory construction body used in this method. This invention relates to a dryness measuring element.

(Prior art) In the case of monolithic refractory construction bodies such as blast furnace tilting troughs, there are many that use water as a binder, or that are mixed and poured with water like concrete, and are then constructed using vibration. After construction, such a monolithic refractory construction body is heated and dried using a burner, for example. If the drying of the monolithic refractory construction body after construction is insufficient, it may be used as a refractory after this. 80 years before or by the commencement of its use.
When heated to 0°C or higher, free water inside the monolithic refractory construction evaporates, and an explosion occurs due to the increase in vapor pressure. Such explosions can damage the monolithic refractory construction body and pose a hazard to surrounding workers, so it is necessary to prevent them as much as possible.

It is known that the occurrence of the above-mentioned explosion is largely related to the air permeability and tensile strength of the material used for the monolithic refractory construction body. That is, when the saturated water vapor pressure of free water inside the monolithic refractory construction exceeds the tensile strength of the monolithic refractory construction, an explosion occurs. Therefore, the above-mentioned heating drying is carried out at a temperature determined empirically such that the saturated vapor pressure of free water does not exceed the tensile strength of the monolithic refractory construction body.

In addition, conventionally, whether or not to finish heating drying of a monolithic refractory construction body was determined by detecting the temperature of the monolithic refractory construction body and determining whether or not the temperature rose to a predetermined reference temperature. . In other words, a thermocouple is buried in the monolithic refractory construction during construction, the temperature of the monolithic refractory construction is monitored during heating and drying, and the temperature of the monolithic refractory construction is set to a predetermined reference temperature determined empirically. For example, when the temperature reaches 150° C. or higher, drying is considered to have been completed.

[Problem that the invention seeks to solve]

In this conventional method, the point at which drying is considered to be completed is determined based on the temperature of the monolithic refractory construction.
It is known that the temperature that should be used as the basis for determination differs depending on the material and the shape of the monolithic refractory construction body. Therefore, when forming a monolithic refractory construction body using a newly developed material or a monolithic refractory construction body with a shape different from the conventional one, it is necessary to set the appropriate heating temperature for the material and shape. It is customary to repeat the experiment several times in order to determine the above-mentioned reference temperature. Further, at this experimental stage, explosions often occur when heating to 800° C. or higher during heat drying or after heat drying is completed. In particular, high-strength monolithic refractory construction bodies, which often have dense structures, have low air permeability, so water inside the monolithic refractory construction is easily removed and a large explosion occurs.

Furthermore, with such conventional methods, it is not possible to accurately detect the end point of drying at which there is no danger of explosion, so in order to prevent explosions during heat drying, special care is taken to heat dry at low heat for a very long time. It is customary to do so. Therefore, wasteful heating and drying is performed after the actual drying is completed.

[Means for solving problems]

The present invention has been made in consideration of the above circumstances, and includes a method for detecting the end of drying of a monolithic refractory construction body, which can accurately detect the end point of drying when the danger of explosion is eliminated, and a method used in this method. The object of the present invention is to provide a dryness measuring element for a monolithic refractory construction body.

In order to achieve the above-mentioned object, in the drying end detection method of a monolithic refractory construction body according to the present invention, a pair of electrodes are buried inside the monolithic refractory construction body at a predetermined interval during construction, The end point of drying of the monolithic refractory construction body is detected by measuring the resistance value between both electrodes and detecting that free water in the monolithic refractory construction body has disappeared.

Free water in the monolithic refractory construction body accumulates in the voids of the monolithic refractory construction body, and as the free water evaporates, the electrical resistance value between both electrodes gradually increases. When the free water in the monolithic refractory construction disappears, both electrodes become electrically insulated. After the free water in the monolithic refractory construction is gone, only crystal water and other volatile components will evaporate from the monolithic refractory construction by heating and drying, and the monolithic refractory construction can be completed using medium or high heat. It can dry the body without causing it to explode. Therefore,
The point at which this free water disappears may be defined as the point at which the drying ends.

The resistance value between both electrodes can be detected by applying a predetermined voltage between both electrodes and measuring the voltage value or current value between both electrodes.

In order to prevent explosions during heating and drying, it is necessary to control the temperature of the monolithic refractory construction to such a level that the saturated vapor pressure of free water does not exceed the tensile strength of the monolithic refractory construction. In such temperature control, the temperature is detected by a thermocouple, and the output of a heating means such as a burner is controlled based on the detection result, as in the past. Preferably, in order to further shorten the time required for the heating drying process of the monolithic refractory construction body, it is preferable that the amount of free water detected as described above be adjusted to a range where no explosion occurs, that is, saturated steam. The heating temperature is controlled to be as high as possible within a range where the pressure does not exceed the tensile strength of the monolithic refractory construction body.

Moreover, the dryness measuring element for a monolithic refractory construction body according to the present invention is a heat-resistant package embedded in a monolithic refractory construction body in order to carry out the dryness measurement method for a monolithic refractory construction body. a pair of electrodes protruding from one end thereof at a predetermined distance so as to protrude into the monolithic refractory construction body; and a pair of electrodes individually coupled to the electrodes within the heat-resistant package; It is characterized by providing a pair of heat-resistant conducting wires led out from the heat-resistant package.

The above heat resistant package is heat resistant, preferably 300°C.
It is made of an electrical insulator having a heat resistance higher than the above. The above heat-resistant package is made of alumina material when the monolithic refractory construction body is made of a neutral material in order to prevent adverse effects on the monolithic refractory construction body under high temperatures. When the monolithic refractory construction body is made of a basic material, it is made of a magnesia material.

Copper wires are usually used for the electrodes. However, when using a highly corrosive binder for the monolithic refractory construction body, a highly corrosion-resistant electrical conductor such as a carbon rod or a stainless steel rod is used.

The voltage applied to both electrodes is preferably 1 to 9V.

If it is less than 1V, it will be susceptible to voltage drop due to contact resistance, and if it is more than 9V, it will generate more heat if the conductor is short-circuited, and there is a risk of fire. If it is 1 to 9■, a portable power source such as a dry cell battery can be used as the power source.

Copper wire, etc., which has excellent heat resistance, is used for the above-mentioned conductor wires, but especially when a highly corrosive binder is used in the monolithic refractory construction, the corrosion and heat resistance of stainless steel, etc. is used. Conductive wires made of excellent electrical conductors are used.

In order to prevent explosions during heating and drying, it is necessary to control the temperature of the monolithic refractory construction to such a level that the saturated vapor pressure of free water does not exceed the tensile strength of the monolithic refractory construction. In order to control the temperature of this monolithic refractory construction,
A thermocouple is used as in the past, but it is preferable to bury the thermocouple near the electrode in order to ascertain the condition of the monolithic refractory construction body as accurately as possible. It is also advantageous to save effort in embedding electrodes and thermocouples.

Therefore, in order to improve the accuracy of grasping the condition of the monolithic refractory construction body and improve the workability of embedding electrodes and thermocouples, we have developed A groove for installing a thermocouple is formed in the groove, and the dryness measuring element and the thermocouple can be simultaneously buried in the monolithic refractory construction body with the thermocouple inserted and fixed in this groove. It's advantageous.

Based on past experience, it is preferable to use a stainless steel sheathed chromel-alumel thermocouple (K thermocouple) as the thermocouple.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the case where one Example of this invention is applied to the dryness measurement of a blast furnace tilting gutter is demonstrated.

First, an appropriately selected number (four in this case) of dryness measuring elements 1 for a monolithic refractory construction body and a larger number (eight in this case) of thermocouples 2 are prepared. As the thermocouple 2, a stainless steel sheath type chromel-alumel thermocouple with an outer diameter of 3.2 fi is used.

As shown in FIGS. 2 to 4, the dryness measuring element 1 includes a heat-resistant package 3 made of alumina or magnesia and a pair of copper electrodes 4 protruding from one end of the package at a predetermined distance. , consisting of a pair of copper conductive wires 5 individually connected to the electrodes 4 inside the heat-resistant package 3, twisted together so as to be insulated from each other, and led out from the other end of the heat-resistant pan cage 3.

A groove 6 into which one thermocouple 2 is inserted is formed on the circumferential surface of the heat-resistant package 3 over the entire length from one end to the other end, and one thermocouple 2 is inserted into this groove 6. , is fixed by fixing means 7.

After the monolithic refractory construction body has hardened, they are fixed by the monolithic refractory construction body, so in the case of cold construction, vinyl tape is used as the fixing means 7, but in the case of hot construction. A material having a certain degree of heat resistance, such as wire, is used as the fixing means 7.

As shown in Fig. 1, the blast furnace tilting gutter 8 consists of an iron frame 9, a permanent lining 10 formed along the inner surface of the iron frame 9, and a monolithic refractory construction body 1) as a lining attached to the inside of the iron frame 9.
It consists of. This monolithic refractory construction body 1) is constructed with high strength and high density by kneading the newly developed material with water and then using methods such as pouring and vibration construction.

When constructing the monolithic refractory construction body 1), a dryness measuring element 1 and a thermoelectric sensor are integrated as described above at the boundary between the permanent tension 10 from which moisture is most difficult to remove and the monolithic refractory construction body 1). In addition to burying Pair 2, monolithic refractory construction body 1)
Embed the remaining thermocouple 2 on the surface of.

Each conductor 5 of the dryness measuring element 1 is connected to an electrical resistance moisture meter 1.
2, and each thermocouple 2 is connected to a temperature recorder 13. Further, the thermocouple 2 embedded in the surface of the monolithic refractory construction body 1) and each conducting wire 5 of the dryness measuring element 1 are further connected to a combustion control device (not shown). The moisture meter 12 is further connected to a voltage (or current) recorder 14.

After construction, the monolithic refractory construction body 1) is left for a predetermined curing period to evaporate moisture generated during hardening.

When this curing is completed, the formwork is removed and dried while being heated from the inside with a burner (not shown).

This heating drying is performed to evaporate free water within the monolithic refractory construction body 1), and the amount of free water is detected by applying a predetermined voltage between both electrodes 4 of the dryness measuring element 1. , voltage between both electrodes 4 (unshaped refractory construction body 1 between both electrodes 4)
This is done by detecting the amount of voltage drop caused by the resistance.

The output of the above burner is such that the temperature of the monolithic refractory construction body 1) is below the temperature at which the saturated vapor pressure of the free water detected in this way does not exceed the tensile strength of the monolithic refractory construction body 1). controlled so that For this control, temperature information of the monolithic refractory construction body 1) is fed back to the combustion control device from a thermocouple 2 embedded in its surface, and content information is fed back to the combustion control device. In such a heating drying process, the tensile strength of the monolithic refractory construction body 1) increases in response to a decrease in the water content, and the allowable saturated water vapor pressure can be reset to a higher value. As shown in FIG. 5, a drying schedule can be implemented in which the temperature of the monolithic refractory construction body 1) is increased in stages as the drying progresses.

Here, the temperature of the monolithic refractory construction body 1) was maintained at approximately 150°C for about 43 hours after the start of heating drying, and then the temperature of the monolithic refractory construction body 1) was increased to approximately 250°C for approximately 7 hours. The temperature of the monolithic refractory construction body 1) is maintained at about 250° C. for about 91 hours after the start of heating and drying. During this period, measurement results have been obtained in which the water content increases between 43 and 50 hours after the start of heating drying, but this is due to the evaporation of the water content by increasing the temperature of the monolithic refractory construction body 1). It is considered that this is because the resistance value between the electrodes 4 decreases due to the steam, and thus the measurement results in which the water content appears to increase are obtained. Further, it has been observed that the water content becomes 0.1% or less approximately 70 to 75 hours after the start of heat drying.

Here, we conducted heat drying of a monolithic refractory construction body 1) made of a newly developed material with high strength, toughness, and high density, but the drying schedule for the heat drying was unknown. However, with reference to the predetermined tensile strength of the monolithic refractory construction body 1), heating and drying was carried out based on the water content information obtained through the dryness measuring element 1. In addition to being able to set the drying schedule, we were also able to detect the end point of drying without causing explosions, that is, the point in time when the moisture content was 1% or less and there was no risk of explosions occurring.

〔Effect of the invention〕

As explained above, according to the present invention, by measuring the resistance value between the electrodes buried in the monolithic refractory construction body and detecting that free water in the monolithic refractory construction body has disappeared, The drying end point of the monolithic refractory construction body can be detected. Therefore, it is possible to shorten the heating drying time, which was previously set to be extremely long, to close to the actual heating drying end point, and to omit the so-called wasteful heating drying that is performed after the actual drying has finished. Not only can the time be shortened, but also the energy such as fuel used for heating can be significantly saved.

In addition, corresponding to the measured amount of water content, it is possible to determine the temperature for the saturation pressure of water content that is permissible for the tensile strength of the material of the monolithic refractory construction body, and determines the temperature that will cause explosion during heating and drying. Even when using a new material whose safe temperature is unknown or forming it into a new shape, as long as you know the tensile strength of the material for the monolithic refractory construction, you can find a safe temperature that will not cause an explosion. It is determined based on the measurement results of the water content, and heating and drying can be performed at a temperature below that temperature.

Furthermore, since a safe temperature that will not cause an explosion can be determined based on the measurement results of the amount of water contained, the heating temperature of the monolithic refractory construction body has been determined to be lower than the conventionally set temperature. The temperature can be set high within the range below the temperature, and by heating the monolithic refractory construction body to the high temperature, the heating and drying process can be further shortened.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram schematically illustrating the method for detecting the end of drying of a monolithic refractory construction body according to the present invention, and FIG. 2 is a drying completion detection element for a monolithic refractory construction body according to the present invention. 3 is a plan view thereof, FIG. 4 is a side view thereof, and FIG. 5 is an embodiment of the drying end detection method for a monolithic refractory construction body according to the present invention shown in FIG. FIG. 2 is a characteristic line diagram showing the drying schedule, the water content, and the temperature change over time at the boundary between the surface of the monolithic refractory construction body and the permanent tension. 1 is a dryness measuring element, 2 is a thermocouple, 3 is a heat-resistant package, 4 is an electrode, 5 is a conductor, and 1) is a monolithic refractory construction body. Figure 1 Figure 2 Procedural master's letter (method) June 17, 1985 Michibu Uga, Commissioner of the Patent Office 2. Title of the invention 3. Relationship with the person making the amendment Applicant's address Ako 2 Name of 1576 Higashioki, Ichichuhiro Aza Kawasaki Rozai Co., Ltd. February 51, 1986) (Sent 25, 1985) 6, Drawing subject to amendment 7, contents of amendment as attached.

Claims (3)

[Claims] (1) During construction, a pair of electrodes was buried inside the monolithic refractory construction with a predetermined interval, and the resistance value between both electrodes was measured to determine that free water inside the monolithic refractory construction was eliminated. A method for detecting completion of drying of a monolithic refractory construction body, characterized in that the drying end point of the monolithic refractory construction body is detected by detecting this. (2) A heat-resistant package buried in the monolithic refractory construction body, a pair of electrodes protruding from one end of the package so as to penetrate into the monolithic refractory construction body at a predetermined distance, and the heat-resistant package A dryness measuring element for a monolithic refractory construction body, characterized in that a pair of heat-resistant conductive wires are individually coupled to the electrodes within the heat-resistant package and led out of the heat-resistant package from the other end of the heat-resistant package. (3) The heat-resistant package has a groove on its circumferential surface that is embedded in the monolithic refractory construction body and into which a thermocouple for detecting the temperature of the monolithic refractory construction body is inserted.
Dryness measuring element for monolithic refractory construction bodies described in .